Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species' probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not enforced.

Numerous factors affect the distribution of mangrove plants. Most mangrove species are typically dispersed by water-buoyant propagules, allowing them to take ad...

Climate change, particularly its associated sea level rise, is major threat to mangrove coastal areas, and it is essential to develop ways to reduce vulnerability through strategic management planning. Vulnerability has three dimensions of exposure to stresses, associated sensitivity, and related adaptive capacity, and ways to measure components of each were trialled at sites in Africa and the South Pacific to develop an analysis procedure based on ranking. The approaches of the ranking system for vulnerability assessment of mangrove systems integrate biotic and abiotic factors along with human management components, using validated methods previously developed for other research questions. These include determining mangrove forest health, adjacent ecosystem resilience, the extent and effects of human impacts, and the environmental conditions of different mangrove settings. Results of the vulnerability assessment ranking using up to 20 measurements found all sites to have some components of vulnerability. Douala Estuary, Cameroon showed the highest vulnerability, owing to low tidal range, impacts from non-climate stressors, and evidence of moderate seaward edge retreat. Tikina Wai, Fiji showed inherent vulnerability owing to location on a subsiding coastline with a low tidal range, but this was offset by strong local community management capacity. Rufiji Delta, Tanzania showed inherent resilience owing to location on an uplifting coastline with a macrotidal range, but showed vulnerability from human impacts and lower local community management capacity. The most critical components to the vulnerability assessment were found to be exposure components of relative sea level trends and sediment supply, and sensitivity components of forest health, recent spatial changes and net accretion rates. The results provide a baseline against which to establish long-term ongoing monitoring, allowing continued assessment of the complex dynamics of climate change impacts, and providing an information base for strategic management decisions.

Davidson, J. L., C. Jacobson, A. Lyth, A. Dedekorkut-Howes, C. L. Baldwin, J. C. Ellison, N. J. Holbrook, M. J. Howes, S. Serrao-Neumann, L. Singh-Peterson, and T. F. Smith. 2016. Interrogating resilience: toward a typology to improve its operationalization. Ecology and Society 21(2):27.http://dx.doi.org/10.5751/ES-08450-210227